Long head biceps tenodesis with a knotless cinch suture anchor: a biomechanical analysis

Biomechanical properties of suprapectoral biceps tenodesis with double-anchor knotless luggage tag sutures vs. subpectoral biceps tenodesis with single-anchor whipstitch suture using all-suture anchors

Background

As the use of all-suture anchors continues to increase, limited biomechanical data on the use of these anchors in various configurations for tenodesis of the long head biceps tendon (LHBT) exists. The aim of this study was to compare the biomechanical properties of a 2-anchor luggage tag suprapectoral biceps tenodesis (Sup-BT) vs. a single-anchor whipstitch subpectoral biceps tenodesis (Sub-BT) using all-suture anchors. The hypothesis was that the Sub-BT will have a higher ultimate load to failure and less creep relative to the Sup-BT construct.

Methods

Eighteen fresh frozen cadaveric humeri were used. The specimens were randomly divided into 2 groups of 9; i) The Sup-BT were performed with 2 1.8 mm knotless all-suture anchors using a luggage-tag fixation configuration, ii) The Sub-BT were performed using a single 1.9 mm all-suture anchor and a whipstitch suture configuration with a tied knot. The humeri were tested on a hydraulic MTS machine where the specimens were preloaded at 5 N for 2 minutes and then cyclically loaded from 5 to 50 N for 1000 cycles at 1 Hz while maximum displacement was recorded with a motion system and markers attached to the bone and bicep tendon. The tendon was then tensioned at a rate of 1 mm/s to obtain the ultimate load to failure. CT scans of the specimens were used to calculate the bone mineral density at the site of the anchor/bone interface and video recordings were captured during load to failure to document all modes of failure.

Results

There was no significant difference in the average load to failure of the Sup-BT and Sub-BT groups (197 N ± 45 N (SD), 164 N ± 68 N (SD) respectively; P = .122) or creep under fatigue between the Sup-BT vs. Sub-BT specimens (3.1 mm, SD = 1.5 vs. 2.2 mm, SD = 0.9; P = .162). The bone mineral density was statistically different between the 2 groups (P < .001); however, there were no observed failures at the anchor/bone interface and no correlation between failure load and bone mineral density.

Conclusion

The ultimate load to failure and creep between a Sup-BT with 2 knotless all-suture anchors using a luggage tag suture configuration was equivalent to a Sub-BT with 1 all-suture anchor using a whipstitched suture configuration and a tied knot. Surgeons can perform either technique confidently knowing that they are biomechanically equivalent in a cadaver model at time zero, and they offer similar strength to other fixation methods cited in the literature.

All-Suture Suspensory Button Has Similar Biomechanical Performance to Metal Suspensory Button for Onlay Subpectoral Biceps Tenodesis

Purpose

To evaluate the maximal load at failure, cyclic displacement, and stiffness of onlay subpectoral biceps tenodesis (BT) with an intramedullary unicortical metal button (MB) versus a unicortical all-suture button (ASB).

Methods

Eighteen matched paired human cadaveric proximal humeri were randomly allocated for subpectoral BT with either ASB or MB using a high-strength suture. Specimens were tested on a servohydraulic mechanical testing apparatus under cyclic load for 1,000 cycles and then loaded to failure. The clamp was then adjusted to isolate the suture-anchor point interface and loaded to failure. Maximal load to failure, displacement, and stiffness were compared.

Results

There was no significant difference between groups in stiffness, displacement, or yield load. The maximal load to failure for the MB was greater than the ASB (347.6 ± 74.1N vs 266.5 ± 69.3N, P = .047). Eight specimens in each group failed by suture pull-through on the tendon. When the suture-anchor point interface was isolated, there was no significant difference in maximal load at failure (MB 586.5 ± 215.8N vs ASB 579.6 ± 255.9N, P = .957).

Conclusions

This study demonstrates that the MB and ASB have similar biomechanical performance when used in subpectoral BT. Although the MB showed statistically significant greater maximal load to failure, there was no difference between the MB and ASB when the suture-tendon interface was eliminated. Suture pull-through was the most common mode of failure for both implants, underscoring the importance of the suture-tendon interface.

Clinical Relevance

Fixation techniques for the treatment of long head of the biceps brachii tenodesis continue to evolve. The use of an all-suture suspensory button has advantages, but it is important to understand if this implant is a biomechanically suitable alternative to a metal suspensory button.

The high resistance loop (H-loop) technique used for all-inside arthroscopic knotless suprapectoral biceps tenodesis: A case series

Introduction

Suprapectoral tenodesis is a common technique for the treatment of long head biceps tendon lesions. However, so far, there is no gold standard treatment in all-inside arthroscopy. The purpose of the present study was to introduce and evaluate the functional outcomes of an innovative, all-inside arthroscopic high resistance loop (H-loop, high resistance to tissue cutout and 360° grasping of the tendon) technique for long head of biceps (LHB) tenodesis.

Method

From September 2020 to March 2022, a series of cases of 32 consecutive patients (28 rotator cuff tear with LHBT pathology and 4 superior labrum anterior-posterior (SLAP) tears which including 2 type II and 2 type IV) who received LHB tenodesis using all-inside arthroscopic high resistance loop technique were included in this study. The American Shoulder and Elbow Surgeon Score (ASES), Visual Analog Scale (VAS), Simple Shoulder Test Score (SST), Constant–Murley scores, and University of California at Los Angeles Scoring System (UCLA) were used to evaluate the clinical outcomes of patients in preoperative and final follow-up. Meanwhile, postoperative complications were also observed.

Result

32 patients (14 women and 18 men, average age was 55.7 years) underwent all-inside arthroscopic knotless suprapectoral biceps tenodesis using the H-Loop stitch technique. The mean time of follow-up was 16.2 ± 2.6 months. The ASES, VAS, Constant–Murley, SST, and UCLA scores improved from 51.5 ± 15.8, 5.5 ± 1.6, 57.8 ± 14.7, 5.0 ± 2.8, and 16.1 ± 3.8 preoperatively, to 89.1 ± 7.5, 1.0 ± 0.8, 87.3 ± 5.5, 10.4 ± 1.5, and 31.3 ± 2.6 in the last follow-up, respectively (p < 0.001). During the follow-up, no patients in this study experienced postoperative complications such as infection of the wound, injury of nerves, and hardware failure; no patients required revision after their operation. In addition, none of the patients had cramping or a “Popeye” deformity during follow-up.

Conclusion

This article presents an innovative, all-arthroscopic H-loop technique for LHB tenodesis. This technique for LHB tenodesis showed favorable functional and cosmetic outcomes, as well as high satisfaction rates. Due to its simplicity of operation and satisfactory preliminary clinical outcomes, H-loop technique is perhaps another option to choose in all-inside arthroscopic LHB tenodesis.

Arthroscopic Single-Portal Suprapectoral Biceps Tenodesis With All-Suture Anchor

Tenodesis of the long head of the biceps tendon can be performed through arthroscopic and open techniques with various fixation methods and at different locations on the humerus. Many techniques have been described, with controversy surrounding the advantages and disadvantages of each. In this Technical Note, we describe an all-arthroscopic, intra-articular, single-portal, suprapectoral biceps tenodesis with an all-suture anchor. This technique also allows for suture passage through the biceps tendon before tenotomy to ensure proper maintenance of the length-tension relationship of the biceps musculotendinous unit.

Can a Two Simple Stitches Method Provide Secure Fixation Strength in Biceps Tenodesis?: Biomechanical Evaluation of Various Suture Techniques

Background

The purpose of this study was to compare the initial fixation strength between four different suture methods for the long head of the biceps.

Methods

Forty-eight fresh frozen porcine flexor hallucis longus tendons (mean width at suture site, 8.5 ± 0.9 mm) and phalanx bones were randomly assigned to one of the four arthroscopic biceps tenodesis techniques: simple stitch (SS), mattress suture (MS), lasso-loop (LL), and two simple stitches (2SS). A biceps tenodesis was performed according to the four techniques using all-suture type suture anchors (1.9-mm SUTUREFIX anchor with No. 1 ULTRABRAID sutures). Biomechanical evaluations were performed to test load to failure (N), stiffness (N/mm), stress (N/m²), and mode of failure.

Results

As for the SS, MS, LL, and 2SS, the mean load to failure was 50.9 ± 14.61 N, 82.3 ± 24.8 N, 116.2 ± 26.7 N, and 130.8 ± 22.5 N (p < 0.001), respectively; mean stiffness was 6.1 ± 1.3 N/mm, 6.7 ± 2.6 N/mm, 7.8 ± 1.4 N/mm, and 8.1 ± 4.2 N/mm, respectively (p = 0.258); and mean stress was 0.7 ± 0.3 N/m², 1.4 ± 0.8 N/m², 2.9 ± 0.7 N/m², and 2.7 ± 0.8 N/m², respectively (p < 0.001). All the failures happened by the suture cutting through the tendon along its longitudinal fibers.

Conclusions

Neither the SS nor the MS method was enough to securely fix the biceps tendon with a significantly lower mechanical strength; however, the 2SS method showed similar initial fixation strength as the LL technique.

Early success of the arthroscopic-assisted locked loop suprapectoral biceps tenodesis

Background

There is wide variability in surgical technique for biceps tenodesis. Prior biomechanical studies have demonstrated superior ultimate and fatigue strength with a Krakow-type locked loop when compared with simple suture and lasso-loop configurations; however, this had not yet been clinically studied. The purpose of this study was to assess the short-term results an arthroscopic-assisted locked loop (ALL) suprapectoral biceps tenodesis technique.

Methods

All patients who underwent an ALL suprapectoral biceps tenodesis by a single surgeon from 2012 and 2019 with a minimum of 12-month follow-up were analyzed. Data collected included demographics, surgical indications, concomitant operative procedures, and postoperative complications of anterior shoulder "groove" pain, "Popeye deformity," biceps muscle cramping pain, and need for revision surgery.

Results

Forty patients who underwent an ALL suprapectoral biceps tenodesis met inclusion criteria. Patients were 55.6 ± 8.6 years of age, consisting of 28 men (57%) and 21 women (43%). The median follow-up was 19.3 months. At the latest follow-up, 1 (2%) patient had anterior shoulder "groove" pain, and no patients had a Popeye deformity or biceps muscle cramping. There were no revision biceps tenodesis procedures.

Conclusion

The ALL suprapectoral biceps tenodesis technique results in a low incidence of postoperative complications. At a short-term follow-up of 1 year, no patients had reoperations or revisions for failed biceps tenodesis. Groove pain was nearly absent in this series of patients.

A Systematic Review and Meta-analysis of Biceps Tenodesis Fixation Strengths: Fixation Type and Location Are Biomechanically Equivalent

PURPOSE

The purpose of this meta-analysis and systematic review was to critically evaluate the biomechanical outcomes of different fixation constructs for a variety of biceps tenodesis techniques in cadaveric models based on both type of fixation and location.

METHODS

A PROSPERO-registered systematic review (CCRD42018109243) of the current literature was conducted with the terms "long head of biceps" AND "tenodesis" AND "biomechanics" and numerous variations thereof in the PubMed, Embase, and Cochrane databases, yielding 1,460 abstracts. After screening by eligibility criteria, 18 full-text articles were included. The individual biomechanical factors evaluated included ultimate load to failure (in newtons), stiffness (in newtons per millimeter), and cyclic displacement (in millimeters). After reviewing the included literature, we performed a quality analysis of the studies (Quality Appraisal for Cadaveric Studies scale score) and a meta-analysis comparing raw mean differences in data between the suprapectoral and subpectoral fixation location groups, as well as between the fixation construct groups.

RESULTS

Among the 18 included studies, 347 cadaveric specimens were evaluated for ultimate load to failure, stiffness, and cyclic displacement when comparing both location (suprapectoral vs subpectoral) and tenodesis fixation type (interference screw vs cortical button, suture anchor, or all-soft-tissue techniques). Interference screw fixation showed significantly greater mean stiffness by 8.0 N/mm (P = .013) compared with the other grouped techniques but did not show significant differences when evaluated for ultimate load to failure and cyclic displacement (P = .28 and P = .18, respectively). Additionally, no difference in construct strength was seen when comparing the fixation strength of suprapectoral versus subpectoral techniques for stiffness, ultimate load to failure, and cyclic loading (P = .47, P = .053, and P = .13, respectively).

CONCLUSIONS

In this meta-analysis, no significant biomechanical differences were found when the results were stratified by specific surgical technique (interference screw vs other tenodesis techniques) and location (suprapectoral vs subpectoral biceps tenodesis).

CLINICAL RELEVANCE

As a result of this study, when biomechanically evaluating specific tenodesis constructs, the individual clinician has the liberty of choosing the fixation technique based on his or her preference and knowledge of shortcomings of each type of fixation construct.

High-Tensile Strength Tapes Show Greater Ultimate Failure Load and Less Stiffness Than High-Tensile Strength Sutures in a Subpectoral Biceps Tenodesis Porcine Model

Purpose

To compare the biomechanical properties of high-tensile strength tape and a high-tensile strength suture in subpectoral biceps tenodesis using a suture anchor in a porcine tendon model.

Methods

A total of 24 artificial composite (polymer and glass fiber) humeri and porcine flexor profundus tendons were used. Two types of suture materials, high-tensile strength sutures (group S) and high-tensile strength tapes (group T), were evaluated. After we inserted metallic suture anchors with either 2 sutures or tapes 5 cm from the superomedial corner of the greater tuberosity, a Krackow suture technique was used to secure the tendons. After a preload of 5 N for 2 minutes, a cyclic loading test from 5 to 70 N was conducted for 500 cycles. Finally, the specimen was loaded to failure at a rate of 1 mm/s.

Results

There were no significant between-group differences in elongation after cyclic loading and elongation at failure load for group S and group T (P = .977 and .630, respectively). The ultimate failure loads in group T (278.2 ± 54 N) were significantly greater than those in group S (249.4 ± 32 N) (P = .028). In contrast, the stiffness values in group T (28.5 ± 4.0 N/mm) were significantly lower than those in group S (32.3 ± 4.5 N) (P = .028). Ten specimens in group S and 8 specimens in group T failed, with tendons being cut through by the sutures, whereas the other 2 specimens in group S and 4 specimens in group T failed due to suture breakage.

Conclusions

Using high-tensile strength tapes in subpectoral biceps tenodesis using a suture anchor leads to significantly greater ultimate failure load as compared with using high-tensile strength sutures in a porcine model. Although lower levels of stiffness were found in high-tensile strength tape group, the difference in the means were not large between 2 groups.

Clinical Relevance

A strong suture–tendon structure may prevent clinical failure of a subpectoral biceps tenodesis using a suture anchor.

Intra-articular arthroscopic biceps tenodesis with interference screw: clinical and isokinetic evaluation

Background

Although biceps tenodesis has been widely used to treat its pathologies, few studies looked at the objective evaluation of elbow strength after this procedure. The purpose of this study is to clinically evaluate patients submitted to long head of the biceps (LHB) tenodesis with interference screws through an intra-articular approach and analyze the results of an isokinetic test to measure elbow flexion and forearm supination strengths.

Methods

Patients who had biceps tenodesis were included in the study if they had a minimum follow-up of 24 months. Patients were excluded if they had concomitant irreparable cuff tears or previous or current contralateral shoulder pain or weakness. Postoperative evaluation was based on University of California-Los Angeles (UCLA) shoulder score and on measurements of elbow flexion and supination strength, using an isokinetic dynamometer. Tests were conducted in both arms, with velocity set at 60º/s with 5 concentric-concentric repetitions.

Results

Thirty-three patients were included and the most common concomitant diagnosis were rotator cuff tear (69%) and superior labrum anterior to posterior (SLAP) lesions (28%). The average UCLA score improved from 15.1 preoperatively to 31.9 in the final follow-up (P < .001). Isokinetic tests showed no difference in peak torque between the upper limbs. One patient had residual pain in the biceps groove. None of the patients had Popeye deformity. UCLA score and follow-up length did not demonstrate correlation with peak torque.

Conclusion

Arthroscopic proximal biceps tenodesis with interference screw, close to the articular margin, yielded good clinical results. Isokinetic tests revealed no difference to the contralateral side in peak torque for both supination and elbow flexion.

Are Implant Choice and Surgical Approach Associated With Biceps Tenodesis Construct Strength? A Systematic Review and Meta-regression

BACKGROUND

Despite the increasing use of biceps tenodesis, there is a lack of consensus regarding optimal implant choice (suture anchor vs interference screw) and implant placement (suprapectoral vs subpectoral).

PURPOSE/HYPOTHESIS

The purpose was to determine the associations of procedural parameters with the biomechanical performance of biceps tenodesis constructs. The authors hypothesized that ultimate failure load (UFL) would not differ between sub- and suprapectoral repairs or between interference screw and suture anchor constructs and that the number of implants and number of sutures would be positively associated with construct strength.

STUDY DESIGN

Meta-analysis.

METHODS

The authors conducted a systematic literature search for studies that measured the biomechanical performance of biceps tenodesis repairs in human cadaveric specimens. Two independent reviewers extracted data from studies that met the inclusion criteria. Meta-regression was then performed on the pooled data set. Outcome variables were UFL and mode of failure. Procedural parameters (fixation type, fixation site, implant diameter, and numbers of implants and sutures used) were included as covariates. Twenty-five biomechanical studies, representing 494 cadaveric specimens, met the inclusion criteria.

RESULTS

The use of interference screws (vs suture anchors) was associated with a mean 86 N-greater UFL (95% CI, 34-138 N; P = .002). Each additional suture used to attach the tendon to the implant was associated with a mean 53 N-greater UFL (95% CI, 24-81 N; P = .001). Multivariate analysis found no significant association between fixation site and UFL. Finally, the use of suture anchors and fewer number of sutures were both independently associated with lower odds of native tissue failure as opposed to implant pullout.

CONCLUSION

These findings suggest that fixation with interference screws, rather than suture anchors, and the use of more sutures are associated with greater biceps tenodesis strength, as well as higher odds of native tissue failure versus implant pullout. Although constructs with suture anchors show inferior UFL compared with those with interference screws, incorporation of additional sutures may increase the strength of suture anchor constructs. Supra- and subpectoral repairs provide equivalent biomechanical strength when controlling for potential confounders.

The Double Krackow Suture Technique Does Not Offer a Significant Benefit Compared to the Krackow Suture Technique in Subpectoral Biceps Tenodesis Using a Double-Loaded Suture Anchor

PURPOSE

To compare the biomechanical properties of the double simple suture (DSS) technique, Krackow suture (KS) technique, and double Krackow suture (DKS) technique in subpectoral biceps tenodesis using a double-loaded suture anchor in a porcine tendon model.

METHODS

A total of 30 artificial composite (polymer and glass fiber) humeri and porcine flexor profundus tendons with diameter of 4.5 mm were used. The sample size was determined based on the results of the pilot study. Metallic suture anchors with double-loaded No. 2 braided sutures were inserted at the subpectoral tenodesis site, 5 cm from the superomedial corner of the greater tuberosity. Three suture techniques were used to fix the tendons: a DSS used as the control, a KS, and a DKS, which is an alternative tendon graft fixation technique. A preload of 5 N was applied for 2 minutes, followed by cyclic loading for 500 cycles ranging from 5 to 70 N; next, a load-to-failure test at 1 mm/s was performed.

RESULTS

The KS (283.5 ± 57 N) and DKS (270.4 ± 50 N) groups had significantly greater ultimate failure loads as compared with the DSS group (84.1 ± 6.4 N) (P < .001). Meanwhile, the peak displacement at failure loads in the KS group (9.3 ± 2.2 mm) and DKS group (7.8 ± 1.7 mm) were significantly smaller than that of the DSS group (11.3 ± 2.9 mm) (P = .015). Stiffness in the DSS group (36.4 ± 3.0 N/mm), KS group (39.6 ± 2.5 N/mm), and DKS group (36.9 ± 4.6 N/mm) was not significantly different (P = .125). All DSS constructs and 6 KS constructs failed with tendons being cut through by the sutures, whereas the other 4 KS constructs and all DKS constructs failed resulting from suture breakage.

CONCLUSIONS

In this subpectoral biceps tenodesis model, both the KS technique and the DKS technique had similar time 0 biomechanical properties that were better than those of the double simple suture technique.

CLINICAL RELEVANCE

A sturdy suture-tendon structure could prevent clinical failure of a subpectoral biceps tenodesis using a suture anchor.

The new LassoLoop360° technique for biomechanically superior tissue grip

PURPOSE

Suprapectoral tenodesis is a frequently used technique for treating pathologies of the long head of the biceps brachii (LHBB) tendon. However, so far, no Gold Standard treatment exist. Hence, the arthroscopic LassoLoop360 (LL360) technique is introduced aiming to provide secure fixation and improved biomechanical properties. It was hypothesized, that the LL360 technique would show superior biomechanical response to cyclic loading and ultimate load-to-failure testing compared to the commonly used simple Lasso Loop (SLL).

METHODS

Twenty-two porcine superficial flexor digitorum tendons were prepared using a No. 2 suture according to either the SLL or the LL360 technique. Displacement after cyclic loading (1.000 cycles) between 5 and 30 N, ultimate load-to-failure (ULTF), mode of failure as well as the construct stiffness were tested.

RESULTS

Significantly less displacement was found in the LL360 group (SLL 2.25 ± 0.51 mm; LL360 1.67 ± 0.37 mm; p = 0.01). Ultimate Load to Failure was significantly higher in the LL360 (168.6 ± 29.6 N) as compared to the SLL (124.1 ± 25.8 N, p = 0.02). The LL360 also revealed a significant higher stiffness compared to the SLL (SLL 13.1 ± 0.9 N/mm vs. LL360 19.1 ± 1.0 N/mm, p < 0.001). The most common mode of failure was the suture cutting through the tendon, with a significantly less suture cutting through for the LL360 compared with the SLL (p < 0.05).

CONCLUSION

The LassoLoop360-technique offers superior biomechanical characteristics regarding the tendon-suture-interface compared to the SLL. In the initial healing phase, the suture-tendon-interface is the most vulnerable part of the tendon-suture-anchor construct, the aim of this new technique is to reduce this weakest part of the chain (Ponce et al., Am J Sports Med 39:188-194, 2011). This technique may therefore be beneficial for arthroscopic suprapectoral biceps tenodesis at the entrance of the bicipital groove.

A biomechanical comparison of two arthroscopic suture techniques in biceps tenodesis: whip-stitch vs. simple suture techniques

BACKGROUND

The aim of this study was to compare the biomechanical performance of whip-stitch (WS) and simple suture techniques (SST) of the long head of the biceps tendon in suprapectoral intraosseous tenodesis with interference screw fixation.

METHODS

A total of 10 paired cadavers (61.1 ± 4.6 years) were randomized to receive WS or SST biceps tenodesis beginning at the musculotendinous junction. Both groups implemented a No. 2 FiberLoop wire and underwent suprapectoral fixation with a polyetheretherketone interference screw at the bicipital grove. A Materials Testing System performed cyclic testing (500 cycles), followed by load to failure at 1 mm/s. Load, displacement, and time were recorded during cyclic and failure testing. A 2-tailed Student's t-test and χ2 analysis were performed for failure load and mode of failure, respectively.

RESULTS

Two SST specimens and 1 WS specimen failed during cyclic loading via tendon rupture at the screw-tendon interface. There was no significant statistical difference in the cyclic displacement after 500 cycles between the WS (12.9 mm ± 4.4 mm) and SST groups (14.0 mm ± 3.8 mm, P = .2); cyclic strain, defined as the peak displacement at the 500th cycle divided by the initial gauge length, between the WS (0.4 ± 0.2) and SST groups (0.7 ± 0.7, P = .3); maximal load (162.7 N ± 56.8 N vs. 153.1 N ± 39.3 N, respectively, P = .6); and stiffness (50.5 N/mm ± 17.7 N/mm vs. 43.3 N/mm ± 10.9 N/mm, respectively, P = .3). All specimens ruptured at the screw-tendon interface.

CONCLUSION

The WS technique can provide equivalent biomechanical performance to the SST in suprapectoral intraosseous biceps tenodesis with interference screw fixation.

Editorial Commentary: Size Matters: Biomechanical Analysis of All-Suture Suture-Anchor Fixation Compared to Conventional Suture Anchors and Interference Screws for Biceps Tenodesis

Anchors and screws demonstrate similar fixation properties for shoulder biceps tenodesis allowing healing, but anchors requiring smaller drill holes reduce the risk of postoperative fractures under torsional stress. Clinicians could create the smallest possible holes in the humerus, especially in throwing athletes who create large torsional stresses.

Biomechanical Analysis of All-Suture Suture Anchor Fixation Compared With Conventional Suture Anchors and Interference Screws for Biceps Tenodesis

PURPOSE

To compare the biomechanical properties of all-suture suture anchors (ASSAs) with conventional interference screws (CISs) and conventional suture anchors (CSAs) for long head of the biceps tendon fixation during proximal biceps tenodesis (BT).

METHODS

We randomized 21 fresh-frozen human cadaveric shoulders into 3 subpectoral BT treatment groups: ASSA, CSA, and CIS. Each construct was cyclically loaded from 5 to 70 N for 500 cycles (1 Hz). All specimens that survived cyclic loading were then pulled to failure (1 mm/s). Elongation, maximum load, energy, and failure mode were recorded. The humerus was stripped of tissue and then subjected to torsional displacement at a rate of 1°/s until fracture occurred. Maximum load, displacement, stiffness, and energy were recorded.

RESULTS

During tendon testing, 3 specimens (43%) in the CIS group failed early during cyclic testing by the tendon tearing at the screw-tendon interface. All other specimens in the CIS group, as well as all specimens in the ASSA and CSA groups, survived cyclic testing and failed during pull-to-failure testing. Failure occurred at the tendon-anchor or -screw interface in all specimens (100%), with no anchor or screw pullout. The CIS group had significantly decreased elongation (8.9 ± 2.23 mm) at maximum load compared with the ASSA (19.2 ± 5.2 mm) and CSA (18.9 ± 2.23 mm) groups (P = .001). During torsional testing, the ASSA group was able to withstand significantly greater torsional displacement (9.22° ± 0.86°) before failure and had greater energy to failure (497.3 ± 45 Nmm-degrees) than the CIS group (6.13° ± 1.24° and 256.6 ± 70.3 Nmm-degrees, respectively; P = .005).

CONCLUSIONS

This study shows that the biomechanical properties of ASSA, CSA, and CIS constructs are similar. The interference screw group had lower tendon elongation at maximum load but had several early failures compared with the suture anchor groups. The use of suture anchors results in maximum tendon and torsional bone loads similar to interference screws for the long head of the biceps tendon. Torsional testing of the CIS resulted in spiral fractures traversing the screw tunnel in 100% of the specimens, which was not found in the suture anchor groups.

CLINICAL RELEVANCE

The ASSA is a viable fixation method for BT in comparison with the CSA and CIS.

Biomechanical Analysis of Medial-Row All-Suture Suture Anchor Fixation for Rotator Cuff Repair in a Pair-Matched Cadaveric Model

PURPOSE

To compare the biomechanical properties of all-suture suture anchors (ASSAs) with conventional suture anchors (CSAs) for double-row rotator cuff repair (RCR).

METHODS

Fourteen fresh-frozen human cadaveric shoulders were randomized into 2 RCR treatment groups: ASSA and CSA. All constructs received a double-row repair, with the lateral-row implants consisting of two 5.5-mm PEEK (polyether ether ketone) Footprint anchors. Each construct was loaded to a 10-N preload for 2 minutes, followed by cyclic loading from 10 to 160 N at a rate of 100 N/s for 100 cycles. Load-to-failure testing was performed immediately after cyclic loading testing at 1 mm/s from the zero position until failure. Cyclic creep, elongation amplitude, maximum load, stiffness, energy, and failure mode were recorded.

RESULTS

No significant difference in cyclic creep (P = .117) or elongation amplitude (P = .428) was found between the ASSA and CSA groups during cyclic testing. Three specimens in each group (43% in each) failed by the suture tearing through the tendon. The remaining specimens in each group failed by the anchor pulling out of the humeral head. The mean maximum load was 617.73 ± 177.77 N and 545.13 ± 212.98 N for the ASSA and CSA groups, respectively (P = .339). Maximum elongation before failure was not different between groups (P = .122). Mean energy and stiffness were not statistically different between the ASSA and CSA groups (P = .629 and P = .973, respectively).

CONCLUSIONS

In this cadaveric analysis with a simplified unidirectional experimental setup, failure mechanics and maximum load between the ASSA and CSA constructs were similar, with no difference in energy and stiffness. Although the ASSA group showed slightly larger elongation than the CSA group, these differences may not be clinically relevant.

CLINICAL RELEVANCE

This study provides a biomechanical head-to-head comparison of ASSAs and CSAs, indicating that ASSAs may be clinically equivalent to CSAs for use in an RCR.

Arthroscopic extra-articular suprapectoral biceps tenodesis with knotless suture anchor

Tenodesis of the long head of the biceps tendon is a frequently performed procedure during shoulder arthroscopy. Various open and arthroscopic techniques have been described with comparable outcomes and complication rates. We describe a simple, knotless, arthroscopic extra-articular biceps tenodesis technique using a 4.5-mm knotless anchor. This technique avoids the complications associated with open tenodesis surgery while still removing the diseased biceps tendon from the bicipital groove. The benefits from knotless suture anchor include no requirement of arthroscopic knot tying and no risk of the knot irritation under the coracoid and coracoacromial ligament.

Biomechanical properties of suprapectoral biceps tenodesis: double knotless screw fixation is superior to single knotless screw fixation

INTRODUCTION

The purpose of this study is to biomechanically evaluate a new technique of double knotless screw fixation for suprapectoral biceps tenodesis and compare the results with that of the single knotless screw fixation as well as the interference screw fixation.

METHODS

24 fresh-frozen human cadaveric shoulders with a mean age of 68.3 ± 9 years were studied. The specimens were randomly divided into three experimental biceps tenodesis groups (n = 8): single knotless screw, double knotless screw and interference screw. Each tenodesis specimen was mounted on a mechanical testing machine, preloaded for 2 min at 5 N, tested with cyclic loading from 5 to 70 N for 500 load cycles and subjected to an axial load to failure test (1 mm/s). The ultimate failure load, stiffness, cyclic displacement and mode of failure were evaluated.

RESULTS

The interference screw fixation had the highest ultimate failure load (215.8 ± 43.1 N) and stiffness (25.7 ± 5.2 N/mm) which were significantly higher than the corresponding results for the single and double knotless screw groups (P = 0.0029). The double knotless screw group had the second highest ultimate failure load (162.8 ± 13.8 N) and stiffness (15.1 ± 4.1 N/mm) which were significantly higher than the corresponding results for the single knotless screw technique (P = 0.0002). The most common mode of failure was suture slippage for both the double (7/8) and single knotless screw (6/8) groups while biceps tendon tearing occurred most often for the interference screw group (6/8).

CONCLUSION

In this biomechanical study, the double knotless screw fixation was found to have a significantly greater ultimate failure load and stiffness than the single knotless screw fixation but lower values than the interference screw fixation.

Biomechanical Evaluation of a Transtendinous All-Suture Anchor Technique Versus Interference Screw Technique for Suprapectoral Biceps Tenodesis in a Cadaveric Model

PURPOSE

To compare the biomechanical properties of an transtendinous all-suture anchor technique with the commonly-accepted interference screw technique in a cadaveric model.

METHODS

Sixteen fresh-frozen human cadaveric shoulders (mean age, 67.6 ± 5.8 years) were used and were randomly divided into 2 experimental long head of the biceps brachii (LHB) tenodesis groups (n = 8), namely transtendinous all-suture anchor technique and interference screw technique. The location of tenodesis was in the bicipital groove, 1 cm distal to the proximal border of the bicipital groove. Tensile force parallel to the longitudinal axis of the humerus was applied to each specimen. A preload of 5 N was applied for 2 minutes, followed by cyclic loading for 500 cycles from 5 to 70 N at 1 Hz; then, a load-to-failure test at 1 mm/s was performed. The ultimate failure load, stiffness, cyclic displacement, failure displacement, and failure modes were recorded.

RESULTS

The transtendinous all-suture anchor technique provided similar ultimate failure load and stiffness as the interference screw technique. However, the cyclic and failure displacements of the transtendinous all-suture anchor technique were significantly greater than the interference screw technique (P = .009 and .021, respectively). Six specimens in the transtendinous all-suture anchor group failed because of suture anchor pullout, while failure of the other 2 was caused by tendon tear; by contrast, all specimens in the interference screw group failed because of tendon tear.

CONCLUSIONS

The transtendinous all-suture anchor technique for LHB tenodesis offered equivalent ultimate failure load and stiffness but had significantly larger cyclic and failure displacement values when compared with the interference screw technique in this cadaveric biomechanical study.

CLINICAL RELEVANCE

The transtendinous all-suture anchor technique is an alternative technique for suprapectoral LHB tenodesis; however, care should be taken because only time zero biomechanical data are available.

Biceps Tenodesis: Biomechanical Assessment of 3 Arthroscopic Suprapectoral Techniques

Biceps tenodesis maintains the cosmetic appearance and length-tension relationship of the biceps with an associated predictable clinical outcome compared with tenotomy. Arthroscopic suprapectoral techniques are being developed to avoid the disadvantages of the open subpectoral approach. This study biomechanically compared 3 arthroscopic suprapectoral biceps tenodesis techniques performed with a suture anchor with lasso loop technique, an interference screw, and a compressive rivet. For a total of 15 randomized paired tests, 15 pairs of human cadaveric shoulders were used to test 1 technique vs another 5 times with 3 customized setups. Biomechanical testing was performed with an electromechanical testing system. The tendon was preloaded with 10 N and cyclically loaded at 0 to 40 N for 50 cycles. Load to failure testing was performed at 1 mm/s until failure occurred. The compressive rivet, interference screw, and suture anchor with lasso loop had mean load to failure of 97.1 N, 146.4 N, and 157.6 N, respectively. The difference in ultimate strength between the suture anchor with lasso loop and the compressive rivet was statistically significant (P=.04). No significant differences were found between the suture anchor with lasso loop and the interference screw (P=.93) or between the interference screw and the rivet (P=.10). When adjusted for sex, the load to failure overall among the 3 constructs was not significantly different. All 3 techniques had a different predominant mechanism of failure. The suture anchor with lasso loop showed superior load to failure compared with the compressive rivet. The minimum load to failure required to achieve clinically reliable biceps tenodesis is unknown. [Orthopedics. 2017; 40(6):e1009-e1016.].

Biomechanical evaluation of two arthroscopic techniques for biceps tenodesis: triple loop suture versus simple suture

BACKGROUND

Several techniques and procedures have been described to treat long head of the biceps pathology; however, tenodesis and tenotomy are the 2 most common procedures performed. This study evaluated the initial fixation strength of the biceps tenodesis triple loop suture (TLS) technique and compared it with that of the simple suture technique (SST).

METHODS

Twenty fresh frozen cadaveric human shoulders (humeral head and neck with attached biceps tendons) were harvested. The biceps tendon was tenotomized proximally before reattachment to the bicipital groove of the matching humerus using suture anchors. Tenodesis was performed using the SST or the TLS technique. Specimens were tested biomechanically for load to failure, stress, and stiffness. The mechanism of failure was evaluated and compared between the 2 suture techniques.

RESULTS

Maximal load to failure was significantly greater using the TLS technique (122.2 ± 26.73 N) than the SST (46.12 ± 14.37 N, P < .001). There was no difference in the mean stiffness (SST: 7.33 ± 4.41 N/mm, TLS: 7.46 N/mm ± 2.67, P = .94). The failure mechanism in all SST samples occurred by suture cutout through the longitudinal fibers of the tendon. In all TLS samples, the failure occurred by suture slippage.

CONCLUSION

This study demonstrated superior load to failure of the TLS compared with the SST technique for biceps tenodesis. Furthermore, this study provides the first description of the TLS technique as a possible application in biceps tenodesis. Clinical application of the TLS must be carefully considered, because although it achieved a superior biomechanical profile, experience with this stitch is limited.